Insecticidal seed coating

ABSTRACT

The present invention relates to an insecticidal coating for a seed comprising one or more binders selected from the group consisting of polymers and copolymers of polyvinyl acetate, methyl cellulose, polyvinyl alcohol, vinylidene chloride, acrylic, cellulose, polyvinylpyrrolidone and polysaccharide and an insecticide wherein the binder forms a matrix for the insecticide; methods for producing said coating and the seed treated with the above described coating. 
     Additionally the invention concerns a method of controlling soil-borne insect pests, particularly Diabrotica spp., comprising applying to a seed an insecticidal coating as described above.

BACKGROUND OF THE INVENTION

Numerous technologies are currently utilized to treat seeds with thedesired purpose of enhancing crop performance. These treatments includeinter alia the coating, pelleting and/or film overcoating of seeds. Arange of fungicide treatments as dusts, liquids and slurries have longbeen used to control soil and seed-borne diseases in vegetable seeds.However, the use of insecticides for vegetable seed treatment has laggedbehind that of fungicide seed treatments, and moreover, seed treatmentof agronomic crops is even less advanced than that for vegetable seed.

Recent developments in seed treatment technology have focused on the useof techniques to deliver pesticides to seeds. Film-coating has beenstudied as a means of delivering insecticides such as benfuracarb,chlorpyrifos, chlorfenvinphos and others. In the past, the concentrationof these insecticides and other active ingredients present in the seedcoating was limited due to direct phytotoxic effect of the insecticideon the seed. Using the instant seed coating of the present inventionsolves the problem of direct insecticide phytotoxicity to the seed.

SUMMARY OF THE INVENTION

The present invention relates to an insecticidal coating for a seedcomprising one or more binders selected from the group consisting ofpolymers and copolymers of polyvinyl acetate, methyl cellulose,polyvinyl alcohol, vinylidene chloride, acrylic, cellulose,polyvinylpyrrolidone and polysaccharide and an insecticidally effectiveamount of an insecticide, preferably an organophosphate, phenyl pyrazoleor pyrethoid insecticide wherein the binder forms a matrix for theinsecticide.

In a preferred embodiment, the invention concerns an insecticidalcoating for a corn seed comprising a binder in an amount from about 0.01to about 15% of the weight of the seed wherein said binder is a vinylacetate-ethylene copolymer or polymer or copolymer of vinylidenechloride, an insecticide in an amount from about 0.005 to about 50% ofthe weight of the seed and selected from the group consisting ofterbufos, chlorpyrifos, fipronil, tefluthrin, chloroethoxyfos andtebupirimfos wherein said binder forms a matrix for the insecticide.

In another preferred embodiment the invention relates to a method ofcontrolling soil-borne insect pests comprising applying to a seed aninsecticidal coating as described above wherein said insecticide isapplied to the seed in an insecticidally effective amount to controlinsect pests.

Additionally the invention concerns a method of preparing a coated seedcomprising a) mixing one or more binders with an insecticide selectedfrom the group consisting of terbufos, chlorpyrifos, tefluthrin,fipronil and tebupirimfos wherein the binder serves as a matrix for theinsecticide; b) applying the mixture to a seed; c) allowing the mixtureto dry on said seed and d) applying a film overcoating to the seed.

In still another embodiment the invention is concerned with a method ofprotecting emerging seedlings of a crop plant from one or more insectorganisms in the seed growing soil environment which comprises applyingto the seeds of the crop plant an insecticidally effective amount of aninsecticidal coating as described herein above.

The seed growing environment as used herein includes that area directlysurrounding the seed and young roots.

Frequently when pesticides are applied to seeds, the pesticide may causephysiological damage to the seed or seedling due to phytotoxic effectsof the concentrated pesticide in or around the seed. The presentinvention is novel in that pesticides may be applied at pesticidallyeffective concentrations without having an adverse effect on theemerging seedling. The amount of insecticidal pesticides that are neededfor control of insect pests is significantly less than has beentraditionally used in granular insecticides. In particular it has beenfound that the use of the coating of the present invention is effectivein the control of insect pests, such as Coleoptera and Lepidopterainsects.

It is a most important object of the present invention to provide a seedcoated. with a coating which protects the seed or the emerging seedlingfrom physiological damage potentially caused by the insecticidalingredient of the coating.

A still further object of the invention is to provide a hybrid corn seedcoated with an insecticide which aids in the control of Diabroticainsects and particularly corn rootworm larvae.

Another object of the invention is to provide a seed which is coatedwith an insecticide whereby the use of the insecticide in the coatingincreases the safety of using said insecticide by reducing operatorexposure.

Still another object of the invention is to provide an insecticidal seedcoating wherein the insecticide is encapsulated within a matrix thatprovides for the controlled release of the insecticide over a prolongedperiod of time.

Yet another aim of the invention is to improve the flowability of seedthrough a seed planter which will ultimately result in more uniform seedplanting.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to improved seed coatings which aresuperior to conventional seed coatings comprising insecticidalcomponents. The invention also relates to the use of insecticides inseed coatings wherein the insecticide has heretofore been ineffectiveagainst certain insect pests, however, when formulated in the seedcoating of the present invention is effective against those same insectpests.

As used herein the term coated seed means a seed that has been subjectedto a procedure whereby the seed is treated with one or more adheringcoating layers.

The coating described herein includes two main components: a) one ormore binders and b) an insecticide. The binder serves as a matrix forthe insecticide.

The binder component of the coating is composed preferably of anadhesive polymer that may be natural or synthetic and is withoutphytotoxic effect on the seed to be coated. The binder may be selectedfrom polyvinyl acetates, polyvinyl acetate copolymers, polyvinylalcohols, polyvinyl alcohol copolymers, celluloses, includingethylcelluloses and methylcelluloses, hydroxymethylcelluloses,hydroxypropylcellulose, hydroxymethylpropylcelluloses,polyvinylpyrolidones, dextrins, malto-dextrins, polysaccharides, fats,oils, proteins, gum arabics, shellacs, vinylidene chloride, vinylidenechloride copolymers, calcium lignosulfonates, acrylic copolymers,starches, polyvinylacrylates, zeins, gelatin, carboxymethylcellulose,chitosan, polyethylene oxide, acrylimide polymers and copolymers,polyhydroxyethyl acrylate, methylacrylimide monomers, alginate,ethylcellulose, polychloroprene and syrups or mixtures thereof.Preferred binders include polymers and copolymers of vinyl acetate,methyl cellulose, polyvinyl alcohol, vinylidene chloride, acrylic,cellulose, polyvinylpyrrolidone and polysaccharide. The above-identifiedpolymers include those known in the art and for example some areidentified as Rhoplex B-60A, Methocel A 15LV, Methocel E15LV, CellosizeQP, AirFlex 500, Daratak SP 1090, Elvanol 85-30, Rhoplex AC-33-NP,Rhoplex B-85 and Vinamul 18132. Particularly preferred classes ofpolymers include polymers and copolymers of vinylidene chloride andvinyl acetate-ethylene copolymers.

The amount of binder in the coating will be in the range of about 0.01to 15% of the weight of the seed. A preferred range will be about 0.1 to10.0% of the weight of the seed.

The binder must be chosen so that it serves as a matrix for theinsectcide. While the binders disclosed above may all be useful as amatrix, the specific binder will depend on the properties of theinsecticide. The term "matrix" as used herein means a continuous solidphase of one or more binder compounds and contains vacancies, voids orspaces occupied by the insecticide and filler. The term matrix is givena broad meaning and includes what may be viewed as a matrix system, areservoir system or a microencapsulated system. In general a matrixsystem consists of an insecticide and filler uniformly dispersed withina polymer, while a reservoir system consists of a separate insecticidephase, insecticide particles or droplets physically dispersed within asurrounding, rate limiting polymeric phase. Microencapsulation includesthe coating of small particles or droplets of liquids. The termmicroencapsulation has not only been applied to coated particles ordroplets but also to dispersions in a solid matrix. Without beinglimited to the spectifc encapsulating system (matrix, reservoir ormicroencapsulated) the term matrix is meant to be inclusive of the abovelisted systems.

Suitable insecticides include those selected from pyrethoids,organophosphates, caramoyloximes, pyrazoles, amidines, halogenatedhydrocarbons, and carbamates and derivatives thereof. Particularlysuitable classes of insecticides include organophosphates,phenylpyrazoles and pyrethoids. Preferred insecticides are those know asterbufos, chlorpyrifos, fipronil, chlorethoxyfos, tefluthrin,carbofuran, imidacloprid, and tebupirimfos. Also included are insectgrowth regulators for example, methoprene and hydroprene. These are wellknown to those skilled in the art.

The amount of the insecticide in the coating will vary depending on thetype of seed and particular active ingredient, but in general will rangefrom about 0.005 to 50% of the weight of the seed. A preferred percentrange for the insecticide is about 0.01 to 40%. A most preferredpercentage range is about 0.05 to 20.0%. In particular, the range forchlorpyrifos will be about 0.5 to 20.0%, a preferred range will be about1.0 to 15%; the range for tefluthrin will be about 0.1 to 10.0%, apreferred range will be about 0.05 to 5.0%; the range for tebupirimfoswill be about 0.01 to 5.0%, a preferred range from about 0.05 to 3.0%;and the range for fipronil will be about 0.01 to 10.0%, and a preferredrange will be about 0.05 to 5.0%.

As one skilled in the art can appreciate the exact amount will varydepending of the size of the seed to be coated. The insecticide of thecoating must not inhibit germination of the seed and should beefficacious during that time in the target insects life cycle whichcauses injury to a crop plant. One skilled in the art will appreciatethat this time will vary depending on the target insect among otherfactors. In general the coating will be efficacious for approximately 0to 120 days after sowing. The coating of the present invention willcontain an amount of insecticide that is insecticidally effective. Aninsecticidally effective amount a used herein means that amount ofinsecticide that will kill insect pests in the larvae or pupal stage ofgrowth or will consisitently reduce or retard the amount of damageproduced by insect pests.

Additionally, when the insecticidal component used for the coating is anoily type formulation it will be desirable to hasten the drying processby drying the formulation. This may be accomplished by means well knownto those skilled in the art and includes the addition of calciumcarbonate, kaolin or bentonite clay, perlite, diatomaceous earth or anyadsorbent material added preferrably concurrently with the insecticidalcoating layer to absorb the oil or excess moisture. The amount ofcalcium carbonate or related compounds to dry charge the solution willbe in the range of about 0.5 to 10.0% (w/w).

The coatings formed by the invention are capable of effecting a slowrate of release of the insecticide by diffusion or movement through thematrix to the surrounding medium.

Virtually any crop seed can be treated in accordance with the invention,such as cereals, vegetables, ornamentals, and fruits. Particular cropseeds are selected from the group of corn (sweet and field), soybean,wheat, barley, oats, rice, cotton, sunflower, alfalfa, sorghum,rapeseed, sugarbeet, Brassica spp., tomato, bean, carrot, tobacco andflower seed, for example, pansy, impatiens, petunia and geranium. Themost preferred seeds include corn and soybean.

Preferred target pest organisms include soil borne insects of the order:

Coleoptera particularly Diabrotica sp. (Western, Southern and Northerncorn rootworm); Melanotus sp. (Corn wireworm); Phyllophaga sp. (Whitegrubs, Wireworms, and False wireworms); Limonius sp. (Sugarbeetwireworms) and Agrrotes sp. (Wheat wireworms, White grubs and Seedmaggots):

Lepidoptera particularly Peridroma sp. (Varigated cutworm); Euxoa sp.(Army cutworm); and Agrotis sp. (Black cutworm):

Diptera particularly Hylemya sp. (Seedcorn maggot) and Tetanops sp.(Sugarbeet root maggot):

Homoptera particularly Pemphigus sp. (Sugarbeet root aphid, Cutworm, andWhite grub) and Aphis sp. (Corn root aphid) .

Most preferred target organisms include in addition to Diabrotica sp,Agrotis ypsilon; melanotus cribulosus; Hylemya cilicrura; Agonoderuslecontei; Feltia subgothica and Phyllophaga rugosa.

In other embodiments a plasticizer may be used in the insecticidalsolution. Plasticizers are typically used to make the film that isformed by the insecticidal coating layer more flexible, improveadhesion, spreadablity and improve the speed during processing. Theimproved film flexibility is important to minimize chipping, breakage orflaking during handling or sowing processes. Many plasticizers may beused however, most preferred plasticizers include polyethylene glycol,glycerol, butylbenzylphthalate, glycol benzoates and related compounds.The range of the percent of plasticizer in the insecticidal coatinglayer will be in the range of about 0.1 to about 20 %.

Materials known in the art as fillers may be used in the insecticidalcoating. Fiillers include woodflours, clays, activated carbon, sugars,diatomaceous earth, cereal flours, fine-grain inorganic solids, calciumcarbonate and the like. Clays and inorganic solids which may be usedinclude calcium bentonite, kaolin, china clay, talc, perlite, mica,vermiculite, silicas,quartz powder, montmorillonite and mixturesthereof. Sugars which may be used include dextrin and maltodextrin.Cereal flours include: wheat flour, oat flour and barley flour.Preferred fillers include perlite, silica and calcium carbonates andmixtures thereof. One skilled in the art will appreciate that this is anon-exhaustive list of materials and that other recognized fillermaterials may be used depending on the seed to be coated and theinsecticide used in the coating.

The filler is chosen so that it will provide a proper microclimate forthe seed, for example the filler is used to increase the loading rate ofthe active ingredient and to adjust the control-release of the activeingredient. A filler aids in the production or process of coating theseed. The effect varies, because in some instances formulatedinsecticidal compounds will comprise a filler. The amount of filler usedmay vary, but generally the weight of the filler components will be inthe range of about 0.005 to 70% of the seed weight, more preferablyabout 0.01 to 45% and most preferably about 0.1 to 15%. The filler maybe supplied in the coating of the invention with the insecticidalcomponent. The specific examples as described herein utilize readilyavailable commercial formulations of known insecticides wherein fillermaterial is included in the formulation.

In addition to the insecticidal coating layer, the seed may be treatedwith one or more of the following ingredients: other pesticidesincluding fungicides and herbicides; herbicidal safeners; fertilizersand/or biocontrol agents. These ingredients may be added as a separatelayer or alternatively may be added in the insecticidal coating layer.

Suitable pesticides include those listed herein and those listed in ThePesticide Manual, 9th Ed., Editor, Charles Worthing, published by theBritish Crop Protection Council and hereby incorporated by reference.

A fungicide may be applied to the seed prior to the coating layerdescribed herein. The application of a fungicide as a dust, slurry orthe like is a well known practice in the art and is not considered acoating layer within the meaning of the term used herein. Suitableexamples of fungicides include Captan(N-(trichloromethyl)thio-4-cyclohexane-1,2-dicarboximide); Thiram(tetramethylthioperoxydicarbonic diamide; Metalaxyl (methylN-(2,6-dimethylphenyl)-N-(methoxyacetyl)-DL-alaninate; Fludioxonil(4-(2,2-difluoro-1,3-benzodioxol-4-yl)-1 H-pyrrol-3-carbonitrile; andOxadixyl (N-(2,6-dimethylphenyl)-2-methoxy-N-(2-oxo-3-oxazolidinyl)acetamide. One skilled in the art will be aware of other beneficialfungicides suitable for combating harmful pathogens which are not only aproblem for a particular locale where the coated seed is to be grown butalso suitable for the protection of seeds in storage before planting.

The amount of fungicide to be added will vary due to the strength of itsactive ingredient, but in general may range from about 0.001 to about10% of the weight of the seed and preferably from about 0.01 to 2.0%.However, for a particular situation the amounts may be greater or less.

Suitable herbicides include those selected from carbamates,thiocarbamates, acetam ides, particularly ch loroacetam ides, triazines,dinitroanilines, glycerol ethers, pyridazinones, uracils, phenoxys,ureas, and benzoic acids and derivatives. Suitable safeners include forexample, benzoxazine, benzhydryl derivatives, N,N-diallyldichloroacetamide, various dihaloacyl, oxazolidinyl and thiazolidinylcompounds, ethanone, naphthalic anhydride compounds, and oximederivatives.

Suitable biocontrol agents are bacteria of the genera Rhizobium,Bacillus, Pseudomonas, and Serratia, fungi of the genera Trichoderma,Glomus, and Gliocladium and mycorrhizal fungi.

The above compounds are listed as examples and are not intended to be anexhaustive list of compounds that can be used in the insecticidalcoating layer or in additional other coating layers.

Conventional means of coating may be used for carrying out the coatingof the invention. Additionally, various coating machines are availableto one skilled in the art. Three well known techniques include the useof drum coaters, fluidized bed techniques and spouted beds. The seedsmay be presized prior to coating. After coating the seeds are dried andthen optionally sized by transfer to a sizing machine. These machinesare known in the art for example, a typical machine used when sizingseed corn in the industry.

Film-forming compositions for enveloping coated seeds are well known inthe art, and a film overcoating can be optionally applied to the coatedseeds of the present invention. The film overcoat protects the coatinglayers and optionally allows for easy identification of the treatedseeds. In general, additives are dissolved or dispersed in a liquidadhesive, usually a polymer into or with which seeds are dipped orsprayed before drying. Alternatively a powder adhesive can be used.Various materials are suitable for overcoating including but not limitedto, methyl cellulose, hydroxypropylmethylcellulose, dextrin, gums,waxes, vegetable or paraffin oils; water soluble or water dispersepolysaccharides and their derivatives such as alginates, starch, andcellulose; and synthetic polymers such as polyethylene oxide, polyvinylalcohol and polyvinylpyrrolidone and their copolymers and relatedpolymers and mixtures of these.

Further materials may be added to the overcoat including optionallyplasticizers, colorants, brighteners and surface active agents such as,dispersents, emulsifiers and flow agents including for example, calciumstearate, talc and vermiculite. Additionally pesticides, such asfungicides may be added to the film coat, however, it has been observedthat fungicides added initially to the seed gives better results thanwhen added with the overcoat. Fluidized bed and drum film coatingtechniques described above can be employed for film coating.

The overcoating film is in the range of approximately 0.01% to about 20%of the weight of the seed it is applied to. The preferred range will beabout 0.01% to about 10.0% and a most preferred range will be about 0.01to 5.0%. A preferred solution will vary depending on the specific activeingredient. A preferred overcoating film may include methyl cellulose,hydroxypropylmethylcellulose, polyvinyl acetate, PEG and mixturesthereof. Additionally, depending on the type of insecticide the overcoatfilm may have incorporated therein a bird repellant compound. Thesecompounds are known in the art and include for example; anthraquinone,methyl anthranilate, capsaicin and oxygenated tetracyclic triterpenoidcompounds (also referred to as cucurbitacins) and disclosed in U.S. Pat.No. 5,292,533. Moreover these compounds may be added to the insecticidalcoating layer as well.

Depending on the germplasm and crop seed to be coated other benefits maybe seen by subjecting the seeds to additional treatments prior tocoating such as priming or treatment with growth regulators andbiocontrol agents.

In seed priming, the seeds are exposed to enough moisture to enhancegermination, but not enough to cause premature germination. Examples ofpriming procedures are known in the art and include drum priming andsteep priming.

Growth regulators which may be added prior to coating includes auxins,cytokinins, gibberellins, ethylene, abscisic acid, IAA, NAA, IBA,ethephon, acetamide, maleic, hydrazide, diminozide and like compounds.Biological treatment may also be used to enhance seed performance andhelp in the control of harmful organisms.

Seeds treated with the coating of the invention have the followingadvantages: They posses less risk with respect to operator handling andexposure because of reduced dust exposure. Pesticides can be applied ina uniform way and loss of pesticides during transport and handling isprevented. Phytotoxicity is reduced to the seeds and developingseedlings and therefore there is no adverse effect on germination,seedling emergence and seedling development. Additionally, placement ofpesticides, particularly insecticides, closer to the insect soil feedingzone may improve insect control.

Specific embodiments of the invention are described hereinafter by wayof example only.

EXAMPLE 1 - SEEDS TREATED WITH AN INSECTICIDAL COATING LAYER

a. Five pounds maize seed pretreated with Captan 400 fungicide andPro-lzed Red colorant, are coated in an Vector LDCS coating machine. Theseeds are warmed for approximately 5 minutes in a rotating pan atapproximately 20 r.p.m. with an air flow of 31-32 c.f.m. and an airpressure of 20 p.s.i. A 992 gram insecticide solution comprising 183grams of 50% chlorpyrifos (the active ingredient in Lorsban 50-SL), 47gram Airflex 500 (vinyl acetate-ethylene), and 762 grams water issprayed onto the seed until all the solution is utilized. Inlet airtemperature is approximately 50° C. and may be periodically adjusted tomaintain seed temperature about equal to or less than 35° C. orgermination may be effected.

b. Seed is treated as described above however, a 304.0 gram insecticidesolution comprising 101.0 grams of 30% tefluthrin (the active ingredientin Force 30CS), 21.0 grams Vinamul 18132 (vinyl acetate-ethylene) and182.0 grams water is applied to the seed.

c. Seed is treated as described above however, a 900 gram insecticidesolution comprising 15.5 grams of 92% tebupirimphos (the activeingredient in MAT 7484), 90 grams Celite 266, 22.5 gram Airflex 500, and772 grams water is applied to the seed.

d. Seed is treated as described above however, a 293 gram insecticidesolution comprising 11.4 grams of 80% fipronil (the active ingredient inRegent), 22.6 grams Celite 266, 9 grams Airflex 500 and 250 grams wateris applied to the seed.

Example 2 - Overcoating of Coated Seeds

a. To each of the seed examples described in Example 1 is added a filmovercoat. The same machine and set points are used for the overcoat. Themachine is set at an inlet temperature of 50° C. which is periodicallyadjusted to maintain seed temperature about equal to or less than 35° C.A solution comprised of 438 grams water, 2.2 grams Methocel K100M, 0.36grams PEG 8000, 5.8 grams Pro-lzed red colorant 0.73 grams GP HytechCalcium stearate 5899 and 2.2.2 grams Afflair is sprayed on the seed for15 minutes.

Example 3 - Seed Germination and Field Emergence Results

Corn hybrid seed germination is tested under testing rules ofAssociation of Official Seed Analysts (AOSA). In addition, seedlingshoots and roots were separated after 7 to 10 days of germination. Dryweight of shoots and roots is recorded to indicate seedling growth. Forfield emergence test, corn hybrid seed is planted in Iowa, Minnesota,Wisconsin, Nebraska, Illinois, and Ohio in a split plot design with tworows per treatment and four replications. Emergence counts are takenevery other day beginning with the first day plants emerge for eachtreatment and continue until 21 days after emergence. The % emergence isdetermined for all locations for each treatment and is exhibited inTable 1. This Table demonstrates that seed coating does not adverselyaffect seedling emergence. The treatments are described as follows:

Treatment 1: Seed is treated as described in Example 1(a);

Treatment 2: Seed is treated as described in Example 1(b);

Treatment 3: Seed is treated as described in Example 1(c);

Treatment 4: Seed is treated as described in Example 1(d);

Treatment 5: Seed is treated with Captan 400 fungicide;

Treatment 6: Seed is treated as described in Example 2;

                  TABLE 1                                                         ______________________________________                                                                             % corn                                   Treatment                                                                             % Germination                                                                            Shoots(mg)                                                                              Roots(mg)                                                                             emergence                                ______________________________________                                        1       99         10.2      12.55   88                                       2       98         --        --      81                                       3       98         13.5      11.6    87                                       4       99          3.1      12.95   86                                       5       99         --        --      87                                       6       99         11.67     13.14   88                                       ______________________________________                                    

Lorsban 50-SL; active ingredient is=o,o-dimethyl O-(3,5,6trichloro-2-pyridyl) phosphorothioate, Dow Elanco

Force 30CS; active ingredient is= 1, 3(Z)!-(±)-(2,3,5,6-tetrafluoro-4-methylphenyl)methyl3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclo-propanecarboxylate,Zeneca, Inc.

Mat 7484; active ingredient=o-2-(1,1-dimethylethly)-5-pyrimidinyl-o-ethyl o-(1-methylethyl)phosphorothioate, Bayer

Regent 80WDG; activeingredient=5-amino-1-(2,6-dichloro-4-trifluoromethyl-phenyl)-3-cyano-4-trifluoromethane sulphinyl pyrazole, Rhone-Poulenc

Example 4 - Corn Rootworm Efficacy Studies

Hybrid corn seeds with and without an insecticidal coating are plantedin Nebraska, Iowa, Minnesota, Wisconsin and Illinois to determine theefficacy of various coated seed treatments in standard tests. All seedscontain a Captan pretreatment whether or not a coating is applied.Additionally, an overcoat layer is applied to all coated seed whichcomprises the coating described in Example 2. Banded granularinsecticides are applied at the manufactures label rates using granularinsecticide applicators. Plot size for each treatment is two ten footrows spaced 30 inches apart with four replications of each treatment ateach location. Non-diaposing 1st instar Western Corn Rootworm larvae areside dressed on both sides of the corn plants in the row at a rate of800 eggs per foot of row. Application of the insect larvae is made whenthe corn seedlings are approximately at the two leaf stage. Theplacement of the larvae is approximately two inches to the side of thecorn plants and two inches below the soil surface. Plots are maintainedwith normal cultural practices until the corn plants reach the floweringstage. At late brown silk stage, 10 sequential roots from each plot areobtained. The corn stalks are cut at approximately 12 inches above thesoil line. Each corn root is washed and after washing the roots arerated on a scale of 1-6 using the Iowa Root Rating Method developed atIowa State University (Hills and Peters, 1971) and used commonlythroughout the corn belt. In the rating, 1=no damage or only a few minorfeeding scars; 2=feeding scars evident but no roots eaten off to within1 1/2inch of the plant; 3=several roots eaten off to within 11/2inch ofthe plant but never the equivalent of an entire node of roots isdestroyed; 4=one root node completely destroyed; 5=two root nodescompletely destroyed and 6=three or more root nodes destroyed. Adestroyed root is defined as a root that has been pruned to within 11/2inch of the base. Pruned roots do not have to originate from a singlenode, but all pruned roots must equal the equivalent of a full node tocount as a destroyed node. The mean root rating results are reported inTable 2 below. In addition, a growth chamber and a greenhouse bioassaywas used to determine the effect of insecticidal seed coating on cornrootworm control. For growth chamber assay, corn seed was planted in a16 oz cup with garden Jiffymix, and allowed to grow for two weeks.Twenty neonate corn rootworm larvae are placed in the Jiffymix near cornroots and allowed to feed for approximately 2 weeks. The larvae are thenscreened out and the % mortality of the larvae is determined. Each cornroot is washed and after washing the roots are rated on a scale of 1-6using the Iowa Root Rating Method developed at Iowa State University(Hills and Peters, 1971). Some of the results are indicated below inTable 3. The greenhouse assay use 2 gallon pot with 20 mesh corn fieldsoil. Forty corn rootworm larvae are placed in each pot when corn plantwas at 4 to 5-leaf stage, and allowed to feed for 2 to 3 weeks. Eachcorn root is washed and after washing the roots are rated on a scale of1-6 using the Iowa Root Rating Method developed at Iowa State University(Hills and Peters, 1971). Some of the results are indicated below inTable 3.

                  TABLE 2                                                         ______________________________________                                        Corn Rootworm Field Efficacy Results                                          Treatment              Root rating                                            ______________________________________                                        Captan only            4.7                                                    Overcoating only       4.5                                                    Example 1(a)           3.43                                                   Example 1(b)           3.0                                                    Example 1(c)           3.2                                                    Example 1(d)           3.55                                                   Lorsban 15 G soil T-band*                                                                            3.0                                                    Aztec 2.1G soil T-band*                                                                              2.8                                                    Force 1.5G soil T-band*                                                                              2.6                                                    ______________________________________                                         *Manufactures label rates and application instructions are followed.     

Lorsban 15 G =15% O,O-dimethyl O-(3,5,6trichloro-2-pyridyl)phosphorothioate, DowElanco

Aztec 2.1 G =2% o- 2-(1,1-dimethylethly)-5-pyrimidinyl-o-ethylo-(1-methylethyl) phosphorothioate and 0.1%cyano(4-fluoro-3-phenoxyphenyl)methyl3-(2,2-dichloroethyl)-2,2-dimethylcyclopropanecarboxylate, Bayer

Force 1.5G =1.5% 1,3(Z)!-(±)-(2,3,5,6-tetrafluoro-4-methylphenyl)methyl3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate,Zeneca, Inc.

                  TABLE 3                                                         ______________________________________                                        Corn Rootworm Bioassay Results                                                          Growth Chamber Greenhouse                                           Treatment  % Mortality Root Rating                                                                             Root Rating                                  ______________________________________                                        Captan only                                                                              27          5.57      4.02                                         Example 1(a)                                                                             87          3.55      3.15                                         Example 1(c)                                                                             96          1.44      2.15                                         Example 1(d)                                                                             80          3.75      --                                           ______________________________________                                    

What is claimed is:
 1. An insecticidal coating for a seed consistingof:a. about 0.01 to 15% by weight of one or more binders selected fromthe group consisting of polymers and copolymers of polyvinyl acetate,methyl cellulose, polyvinyl alcohol, vinylidene chloride, acrylic,cellulose, polyvinylpyrrolidone, and polysaccharide, b. about 0.005 to50% by weight of an insecticidally effective amount of an insecticideselected from the group consisting of terbufos. chlorpyrifos, fipronil,chlorethoxyfos, tefluthrin, carbofuran, imidacloprid, tebupirimfos,methoprene and hydroprene, and c. about 0.01% to about 20% of a filmovercoat selected from the group consisting of methyl cellulose,hydroxypropylmethylcellulose, dextrin, gums, waxes, vegetable orparaffin oils, water soluble or water dispersible polysaccharides andtheir derivatives, alginates, starch, cellulose, synthetic polymers,polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylacetate, polyethylene glycol and polymers and copolymers and mixturesthereof,and optionally water, wherein the binder forms a matrix for theinsecticide on the seed.
 2. The coating of claim 1 wherein the seed isselected from the group consisting of soybean, sugarbeet, sunflower,alfalfa, sorghum, rapeseed and tobacco.
 3. The coating of claim 1wherein the binder is a vinyl acetate-ethylene copolymer or polymer orcopolymer of vinylidene chloride.
 4. Viable seed coated with the coatingaccording to claim
 1. 5. An insecticidal coating for a seed consistingof a binder in an amount from about 0.01 to about 15% of the weight ofthe seed wherein said binder is a vinyl acetate-ethylene copolymer orpolymer or copolymer of vinylidene chloride and an insecticidallyeffective amount of an insecticide selected from the group consisting ofimidicloprid, chlorpyrifos, fipronil, tefluthrin and tebupirimfos and inthe range from about 0.005 to about 50% of the weight of the seed, andabout 0.01% to about 20% of a film overcoat selected from the groupconsisting of methyl cellulose, hydroxypropylmethylcellulose, polyvinylacetate and polethylene glycol, wherein said binder forms a matrix forthe insecticide on the seed.
 6. A method of controlling insect pestsfrom damaging a crop plant comprising applying to a seed an insecticidalcoating according to claim
 1. 7. A method of controlling insect pestsfrom damaging a crop plant comprising applying to a seed an insecticidalcoating according to claim
 5. 8. A method of protecting emergingseedlings of a crop plant from one or more insect organisms in the seedgrowing soil environment which comprises applying to the seeds of thecrop plant an insecticidally effective amount of a coating according toclaim
 1. 9. An insecticidal coating for a seed consisting ofa. about0.01 to 15% by weight of one or more binders selected from the groupconsisting of polymers and copolymers of polyvinyl acetate, methylcellulose, polyvinyl alcohol, vinylidene chloride, acrylic, cellulose,polyvinylpyrrolidone and polysaccharide, b. about 0.005 to 50% by weightof an insecticidally effective amount of an insecticide selected fromthe group consisting of terbufos, chlorpyrifos, fipronil,chlorethoxyfos, tefluthrin, carbofuran, imidacloprid, tebupirimfos,methoprene and hydroprene, and c. about 0.01% to about 20% of a filmovercoat selected from the group consisting of methyl cellulose,hydroxypropylmethylcellulose, dextrin, gums, waxes, vegetable orparaffin oils, water soluble or water dispersible polysaccharides andtheir derivatives, alginates, starch, cellulose, synthetic polymers,polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylacetate, polyethylene glycol and polymers and copolymers and mixturesthereof,and optionally, one or more of water, one or more fungicides orherbicides, or both, a filler selected from the group consisting ofwoodflours, clays, inorganic solids, activated carbon, diatomaceousearth and calcium carbonate, and mixtures thereof, a plasticizer, a birdrepellent compound, a safener, a fertilizer, a biocontrol agent, acolorant, a brightener, a surface active agent ard a seed primer;wherein the binder forms a matrix for the insecticide on the seed. 10.Seed coated with the coating of claim
 9. 11. A method of controllinginsect pests from damaging a crop plant comprising applying to a seed aninsecticidal coating according to claim
 9. 12. A method of protectingemerging seedlings of a crop plant from one or more insects comprisingapplying to the seeds of the crop plant an insecticidally effectiveamount of the coating according to claim 9.